A federal agent removes evidence from the apartment complex where Miriam Carey is believed to have lived in Stamford, Conn., on Oct. 4, 2013. / John Minchillo, AP

by Kevin Johnson, Donna Leinwand Leger and Doug Stanglin, USA TODAY

by Kevin Johnson, Donna Leinwand Leger and Doug Stanglin, USA TODAY

The 34-year-old Connecticut woman who was shot and killed by police after a harrowing high-speed chase from the White House to Capitol Hill was delusional, believing that President Obama was communicating with her, law enforcement officials said Friday.

The officials, who have been briefed on the investigation, spoke to USA TODAY on condition of anonymity because they were not authorized to speak publicly about the ongoing investigation.

Miriam Carey, a dental hygienist from Stamford, Conn., was identified Friday by Washington, D.C., police as the driver of the black luxury sedan that first rammed a barrier at the White House, then sped to Capitol Hill, defying attempts by armed police to stop her Thursday afternoon.

She was shot and killed fleeing her car near the Hart Senate Office Building.

Police in Stamford spoke to Carey in December 2012 after receiving a call from her boyfriend, the law enforcement sources said. She told police then that she thought Obama was eavesdropping on her and the government was electronically monitoring her house. She said she thought she was a prophet, the sources said.

Investigators have been able to trace Carey's movements in the days before the car chase and shooting, said a law enforcement source briefed on the investigation but not allowed to speak publicly.

Carey appears to have taken a direct route from Connecticut to Washington on Thursday. Investigators used New Jersey highway toll records to in part help track her route.

A 1-year-old girl was in Carey's car, though she avoided serious injury and was taken into protective custody.

NBC4 News, quoting law enforcement authorities, also reported that there were indications that Carey thought Obama was stalking her. Carey's mother told ABC News that her daughter began suffering from postpartum depression after giving birth to her daughter last August. "A few months later, she got sick," Idella Carey said. "She was depressed. ... She was hospitalized."

Idella Carey said her daughter had no history of violence and that she had no idea why she was in Washington.

Authorities who descended on Carey's condo in Stamford have not determined a motive for her bizarre behavior through downtown Washington, D.C.

Rep. Michael McCaul, a Texas Republican who chairs the House Committee on Homeland Security, was briefed on the incident by the FBI and secret service.

McCaul said he was told that Miriam Carey had postpartum depression, an injury to her head and a family history of schizophrenia.

He said Carey's boyfriend reported to police that she had been violent on at least one occasion. The boyfriend was worried about Carey's mental state.

McCaul said law enforcement authorities told him that she had a stay in the mental hospital though he didn't know the details. He also said Carey thought that her apartment was under surveillance and that Obama was monitoring her.

"It's the tragic story of a woman with a history of mental illness," McCaul said.

He says authorities found an envelope with white powder at the door of her apartment that has slowed down the search of her apartment.

Miriam Carey's sister Amy Carey-Jones said late Friday that her sister "seemed OK" the last time they spoke more than a week ago, and there were no indications she was unstable.

A second sister, Valarie Carey, a retired New York City police officer, said police should not have used deadly force.

Valarie Carey said there was "no need for a gun to be used."

"That's impossible. She works, she holds a job," said Amy Carey. "She wouldn't be in D.C. She was just in Connecticut two days ago, I spoke to her. ... I don't know what's happening. I can't answer any more."

In Brooklyn, Freddie Perera, 71, a retired traveling salesman, has lived one door down from Amy Carey for four years and said he has seen Miriam Carey a few times while she was visiting.

"When she was here, she was normal," Perera said of Miriam Carey. "They are a pretty nice family."

The New York Daily News quoted Carey's former boss, dentist Brian Evans from Advanced Periodontics, in Hamden, Conn., as saying that she "fell down some stairs and she had a pretty significant head injury" in recent years.

Evans also said that Carey, who was let go last year, had a temper and became incensed over being told to quit parking in a handicapped spot at the medical building. That created friction between them, he said.

Another of Carey's bosses at Advanced Periodontics, dentist Barry Weiss, told NBC Connecticut that she was a bit "headstrong" on a few occasions but was otherwise "an average employee."

Weiss also that said Carey "could be a bit rough," and after complaints from patients, was fired in August 2012.

"Nothing would have led us to think she would have done this," Weiss said.

Another former boss, dentist Steven Oken, for whom she worked eight years, described Carey as a "non-political person" who was "always happy."

A new Facebook page called "In Love Memory of Miriam Carey" features comments from people described as friends and acquaintances. One, purportedly from a former classmate, said Miram "was really just a sweet and nurturing person."

A note at the top from the creator of the page says: "Folks - this is a community page for us to share our feelings on today's tragedy. Keep your politics and hate speech off this page. This is in memory of my friend."

Court records also show that Carey was sued last year by her condo association for failure to pay fees since 2010 on the Stamford home she owned since 2009. The lawsuit, involving $1,759 plus collection costs, was settled in February, the Associated Press reports.

U.S. Capitol Police Chief Kim Dine said the incident "appears to be an isolated, singular matter, with, at this point, no nexus to terrorism."

Two federal officials, who were not authorized to comment publicly, told USA TODAY that all shots were fired by law enforcement officers. One official said no gun was recovered from her car.

"This does not appear to be in any way an accident," Metropolitan Police Chief Cathy Lanier said Thursday. She noted that Carey twice tried to breach security barriers and struck a uniformed Secret Service officer near the White House.

The chaotic events began at 2:12 p.m. ET when the driver rammed a temporary barrier at 15th and E Streets NW, hitting the officer, said Secret Service chief Ed Donovan. Other Secret Service officers chased the woman east on Pennsylvania Avenue but did not shoot.

Lanier said Capitol Police officers pursued the speeding car eastbound and tried to stop it in Garfield Circle, just west of the Capitol lawn. A 23-year-veteran officer suffered non-life-threatening injuries when he crashed into a barrier.

Police had the woman's car surrounded but she escaped, ramming a Secret Service vehicle as she fled. Lanier said police then fired their first shots at the suspect.

The driver made her way onto Constitution Avenue before eventually stopping in the 100 blocks of Maryland Avenue NE, near the Hart Senate Office Building.